1. Richard B. Stuart. ''Applications of Behaviour Theory to Social Casework", in Edwin J. Thomas ed. The Socio-behavioural Application To Social Work. (New York: Council on Social Work Education, 1967) p. 19.
2. Behavior Modification Theory and Practice: A Critical Review
3. Hobart Mowrer, Learning Theory and Personality Dynamics (New York : Ronald Press Co. 1950) p. 483.